Engine Cranks But Doesn’t Run. What Would Be The Reason?

When you have a problem starting your car, basically there are the few things that you need to check. Since the working of engine depends on many components it is not easy to figure out the exact reason for the issue. To diagnose the problem you need to be little more patient and follow a step by step process until you isolate the real cause. This will help you at least identify what went wrong with your vehicle before you approach any automobile service to get your vehicle repaired.
When you have a problem starting your car, basically there are the few things that you need to check. Since the working of engine depends on many components it is not easy to figure out the exact reason for the issue. To diagnose the problem you need to be little more patient and follow a step by step process until you isolate the real cause. This will help you at least identify what went wrong with your vehicle before you approach any automobile service to get your vehicle repaired.

Primarily, an issue with engine can be divided into two scenarios, engine is not cranking and engine is cranking but not starting over. If the engine is not cranking when you turn the ignition key on, then it could be due to weak or dead battery, issue with starter or alternator. In other case, if engine cranks normally but won’t start or fire up then it implies that the battery, starter and alternator are probably fine and there are other possible issues that are making engine to fail.

Engine Is Not Running: Common Possible Reasons
Any engine whether diesel or gasoline, requires proper amount of fuel, a spark at the plug to ignite the fuel and proper compression to operate normally. Having an issue with any one of these may stop the engine from running. Sometimes, you can also anticipate minor issues like failure of the fuse or faulty wiring or short circuit with the connections that supply power to the engine computer (PCM) or fuel pump.

Check For Spark
An ignition system includes components like ignition coil, crankshaft, camshaft sensors, PCM and spark plugs. To check the ignition system first you need to remove one of the spark wire plugs and connect it to the test light or spare spark plug. Ground it near the engine block and test the engine for spark. Do not hold spark plug when you are cranking the engine because you might get shock touching it. If there is a spark in blue colour when you crank the engine then the engine ignition is fine and the problem is with other things like fuel or compression. If no spark appears then you can suspect problem with either cam sensor or wiring or crankshaft sensor. Also check ignition coil because it supplies voltage to create spark at the spark plug. The issue with coil happens especially in rainy season because it fails to transmit the needed amount of ignition to spark plug.

Test Fuel System
First thing is to make sure there is enough fuel in the tank. If it is there, then you might need to check couple of other things to ensure the fuel system is working fine. When the ignition key is turned on, you should hear a buzzing sound from the electric fuel pump. If no sound is heard then it could be due to bad or faulty fuel pump. If the engine contains timing belt, check if is broken or damaged. If the timing belt is broken, the engine will not turn over or ignite. If it is fine, check fuel pump relay and circuit. You can also disconnect fuel line at some point and turn the engine over to see if the fuel is pumping through the line. If not then you can suspect there is an issue with fuel pump operation. Also check for faulty wiring, less fuel pressure, blown fuse or bad relay which can restrict pumping of fuel into the injectors. Sometimes, even the fuel injectors can go bad, faulty or clogged, and block dispense of fuel for ignition.

Check Engine Compression
A proper compression is essential to ignite the fuel and run engine efficiently. Compression is the amount of pressure exerted on the fuel & air mixture before the ignition happens. If enough pressure is not maintained or if any leakage of pressure is there through the valve openings of fuel injector cylinders the engine will not get ignited. This mostly happens when there is loose or jumped timing belt or chain which causes misalignment between camshaft and crankshaft. There is a method to check engine compression using a compression gauge. Any reading of 85 PSI or lower is bad for engine. Anything above 135 PSI indicates that it is working fine. If the variation is too high between cylinders it indicates that the rings and cylinders are worn and the engine needs to be overhauled.

These are just the few things that you can act on if you notice issue with starting of engine. If you cannot troubleshoot and the problem seems too complex then it is better to take the vehicle to an expert.


By: Aaron U. Smith

Article Directory: http://www.articledirectoryusa.com

Source: http://www.articledirectoryusa.com/article/category/vehicles/cars/engine-cranks-but-doesn-t-run-what-would-be-the-reason/

Submitted On Aug 11, 2017. Viewed 19 times.

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